1. Field of the Invention
The invention relates to a holding device or tool holder for boring head tools such as cutting rollers, cutting tools and the like which can be mounted from the rear of the boring head, in particular boring heads of tunnel boring machines, large hole boring machines, shaft boring machines or the like.
2. Description of the Prior Art
Cutting rollers or similar tools are usually attached in holding devices on the front of a boring head. Thus in the case of a tunnel boring machine with the front side facing the face, it is only possible to change the tools when there is access to this front side. In many cases this causes great difficulties and usually also involves dangerous and complicated work. It is therefore especially important to try to find a way of mounting tools from the rear of a boring head.
An extension boring head is known from U.S. Pat. No. 3,444,939 in which cutting rollers are mounted on the inside of the boring head. The bearing covers laid to the rear are fastened by threaded bolts to front bearing pieces or boring head parts. The high stresses occurring during operation must be completely absorbed by the bolts which are thereby subject to the risk of breaking away or fracturing.
Moveover, a holding device for cutting rollers of the type discussed above has become known from U.S. Pat. No. 4,202,418 in which head parts of an unrotatable supporting body designated as a stator can be inserted in a straight line from the rear of the boring head into an accommodating housing forming the holding device until they rest against the front abutments. Intermediate pieces with support surfaces which are substantially forwardly directed, i.e. towards the front of the boring head, are inserted between portions of the head parts which are directed to the rear and stop faces in the holder. The intermediate pieces are held by fastening screws which either engage through bores in the intermediate pieces and are screwed into the holder or which pass through holes in the holder and are screwed into the intermediate pieces or which engage both through bores in the holder and in the intermediate pieces and are screwed into the head parts of the supporting body of the tool. It is only possible to insert the intermediate pieces when the tool which has previously been inserted into the mounting is held in its final position against the abutments. The screwing processes must then be carried out and both the tool and the intermediate pieces must be held.